<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0px;
            padding: 0px;
        }

        .nav {
            list-style: none;
            display: flex;
            width: 800px;
            background-color: aquamarine;
            justify-content: space-around;
            height: 100px;
        }

        .nav li {
            line-height: 100px;
            text-align: center;
            flex: 1;
            background-color: blueviolet;
        }

        .nav li:hover {
            background-color: red;
        }

        .nav li:nth-child(5) {
            order: 1;
            color: bisque;
        }

        .nav li:nth-child(6) {
            order: 2;
            color: bisque;
        }
    </style>
</head>

<body>
    <ul class="nav">
        <li>这是1</li>
        <li>这是2</li>
        <li>这是3</li>
        <li>这是4</li>
        <li>这是5</li>
        <li>这是6</li>
        <li>这是7</li>
        <li>这是8</li>
    </ul>

</body>

</html>